1. Field of the Invention
The present invention relates to a turbofan and an air conditioner having the turbofan, and more particularly, to a turbofan and an air conditioner having the turbofan, which is designed to reduce flow noise at an outlet of the turbofan and to allow air to be smoothly discharged.
2. Description of the Related Art
Generally, a turbofan is a kind of centrifugal fan, which is adapted to radially blow air by rotating blades. The turbofan is applied to a typical air conditioner to blow the air in a desired direction.
FIG. 1 is a cross-sectional view showing an indoor unit of a conventional ceiling type air conditioner, which is equipped with a turbofan. As shown in FIG. 1, the indoor unit of the ceiling type air conditioner includes a case body 2 embedded in a ceiling 1, and a ceiling panel 3 disposed in a lower opening of the case body 2. The case body 2 is provided therein with a turbofan 4, a drive motor 5 to rotate the turbofan 4, and a heat exchanger 6 surrounding the turbofan 4.
The ceiling panel 3, which is provided at a lower face of the case body 2, includes a central inlet 7 formed at a center thereof to draw indoor air, and an outlet 8 formed around the central inlet 7. The central inlet 7 of the ceiling panel 3 is provided with a filter 9 to dean the indoor air drawn therethrough. The ceiling panel 3 is provided above the filter 9 with an air-guide plate 10 having a central opening 10a to guide the indoor air drawn through the filter 9 toward the turbofan 4.
In an operation of the ceiling type air conditioner, as the turbofan 4 rotates by the drive motor 5, the indoor air is drawn into a center of the turbofan 4 through the central inlet 7 of the ceiling panel 3, and the indoor air is radially discharged toward the heat exchanger 6. The indoor air radially discharged from the turbofan 4 is cooled while passing through the heat exchanger 6, and the cool air is again supplied to an interior through the outlet 8.
To cool the drive motor 5 to drive the turbofan 4, the turbofan 4 is positioned such that a rear face of the turbofan 4 is spaced apart from an inner surface 2a of the top plate of the case body 2 by a specific distance, thereby defining a cooling path 11 therebetween. Furthermore, the turbofan 4 is formed at a center area thereof with circulation holes 12 to allow the cool air to be circulated therethrough. A part of the indoor air, radially discharged from the turbofan 4, serves to cool the drive motor 5 while being circulated (in a direction of an arrow A) through the cooling path 11 defined by the rear face of the turbofan 4 and the circulation holes 12.
As such, in the conventional ceiling type air conditioner having the turbofan 4, a part of cooling air, which is radially discharged from the outlet 8 at a high speed, flows along the rear face of the turbofan 4, and the relatively large cooling path 11 is defined between the rear face of the turbofan 4 and the inner surface 2a of the top plate of the case body 2. Thus, since the part of cooling air discharged from the outlet 8 of the turbofan 4 is separated from a supply of main air discharged from the outlet 8, violent turbulent air flow is generated in a region where the air is separated, thereby creating noise.
To overcome the above problems, to cool the drive motor 5 while reducing turbulent air flow by reducing a spacing between the rear face of the turbofan 4 and the inner surface 2a of the top plate is possible. However, in this case, since the air discharged from the outlet 8 of the turbofan 4 largely concentrates at an upper portion of the heat exchanger 6, an efficiency of heat exchange is lowered.